Invetero seems to be based on Chevrolet, judging by the vehicles they make, however, Declasse and Cheval also seem to be based on Chevrolet. They are likely the sub-division of Chevrolet, Corvette.

Invetero's logo is similar to the lighting bolt logo of Opel, a German car brand owned by General Motors, in which Chevrolet is a branch of General Motors. The company's name could be a verbal pun on "in-vitro".

Trivia

The word "in vitro" which Invetero plays on, is a biological term for cultures that are stored or grown in a lab. This may refer to the real-life Corvette being assembled in an individual plant.

The Police chatter rarely refers to the Coquette as a "Declasse" which could imply that Declasse own Invetero as a subsidiary, who exclusively manufacture Coquettes (similar to how Chevrolet manufacture the Corvette as a division of General Motors), or Invetero manufactures Coquettes based on Declasse chassis (like how RUFmanufacture vehicles based on Porsche). This explanation also gives reasons for why the Coquette isn't made by Cheval, the Holden-based brand in Grand Theft Auto V. Given the similarities between the Corvette and the Coquette, the company's real-world equivalent is most likely the EU-only Corvette Europe[1]brand (see Discussion page).